Hello swilsher,
Thank you for participating in the Apple Support Communities. It looks like you can't start up to you’re having trouble installing macOS Mojave. You've tried some good steps to verify that your Mac partition is there and the files are intact. Here are some steps to try next:
First, reset the NVRAM on your Mac using the instructions in How to Reset NVRAM on your Mac. This resets the startup disk selection amongst other things.
If you still can't install, try safe mode by holding down shift when your Mac restarts.
Should the issue persist, feel free to reply with additional details.
Take care.